A conventional method of decorating resin moldings is an in-mold molding technique in which a designed in-mold transfer film and injection resin are combined to have a decorated surface on a resin molding.
FIG. 16 shows a typical layer configuration of an in-mold transfer film 33. The in-mold transfer film 33 includes a carrier section 30 that is composed of a base material film 1 and a release layer 2 and a transfer section 31 that is composed of a hard coating layer 3 and a printed layer 32. The printed layer 32 includes an anchor layer 4, a colored layer 5, and an adhesive layer 6.
The base material film 1 is a base film that constitutes the in-mold transfer film 33. The foregoing layers are formed on the base material film 1. The release layer 2 has the function of completely separating the transfer section 31 formed on the release layer 2. The hard coating layer 3 of the transfer section 31 has the function of protecting a molding from scratches or dust on the outermost layer of the in-mold molding. The anchor layer 4 has the function of joining the hard coating layer 3 and the colored layer 5.
The anchor layer 4 also has the function of adsorbing or anchoring ink in the colored layer 5 and thus is not necessary if ink can be directly joined to the hard coating layer 3. The colored layer 5 is a layer for adding a design to a molding. The colored layer 5 that adds figures and patterns varies in layer configuration, e.g., from a single layer to multiple layers depending on the configurations of figures and patterns. Moreover, the colored layer 5 is formed by gravure printing, screen printing, solvent ink jet printing, and so on. The adhesive layer 6 has the function of joining the colored layer 5 and injection resin and the function of protecting ink in the colored layer 5 from high-temperature and high-pressure injection resin, precluding a flow of ink.
FIGS. 17(A) to 17(D) are explanatory drawings of a typical in-mold molding method.
In FIG. 17(A), the in-mold transfer film 33 having figures and patterns is drawn from a winding body (not shown) and then is supplied between a movable mold 101 and a stationary mold 102 with the transfer section 31 facing a nozzle 41 of the stationary mold 102. The carrier section 30 faces the movable mold 101.
In FIG. 17(B), the in-mold transfer film 33 is sucked and fixed along the molding surface of the movable mold 101 and is shaped along the mold surface shape of the movable mold 101. After that, the movable mold 101 is moved so as to close the movable mold 101 and the stationary mold 102, forming a cavity space 103 between the transfer section 31 and the stationary mold 102.
In FIG. 17(C), high-temperature and high-pressure molding resin 104 is injected into the cavity space 103 toward the transfer section 31 and then is bonded to the transfer section 31.
In FIG. 17(D), a molding 105 cooled to a mold temperature is removed. In this step, when the molds are opened, the transfer section 31 is peeled between the release layer 2 and the hard coating layer 3 and then is removed out of the molds. At this point, the transfer section 31 is transferred to the surface of the molding 105 and thus the hard coating layer 3 serves as the outermost surface of the molding 105, obtaining the molding 105 composed of the transfer section 31 and the molding resin 104.